Amyotrophic lateral sclerosis (ALS, also called Lou Gehrig's disease) is a relentlessly progressive, fatal neurodegenerative disease with a prevalence of about 5 people out of 100,000 each year and an average age of onset of about 60 years. Patients with ALS suffer from degeneration of motor neurons in the brain and spinal cord, which leads to progressive muscular weakness. ALS accounts for about 1/300 to 1/400 of all deaths, which means that about 1,000,000 people now alive in the United States will develop ALS. Death typically occurs 3-5 years after disease onset, due to respiratory paralysis. There is no effective treatment for the disease; the only approved ALS drug (riluzole) extends the lifespan of some ALS patients by only about 3 months. Thus, there remains a need for new therapeutic approaches for treatment of ALS.